swh:1:snp:49cd9498d6cccc5e78252c27dcb645bcf7bf0c91
Tip revision: 74d33293e467df61de1b1d8b2fbe29e550dec33b authored by Linus Torvalds on 03 August 2015, 01:34:55 UTC
Linux 4.2-rc5
Linux 4.2-rc5
Tip revision: 74d3329
rtc-sysfs.c
/*
* RTC subsystem, sysfs interface
*
* Copyright (C) 2005 Tower Technologies
* Author: Alessandro Zummo <a.zummo@towertech.it>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/rtc.h>
#include "rtc-core.h"
/* device attributes */
/*
* NOTE: RTC times displayed in sysfs use the RTC's timezone. That's
* ideally UTC. However, PCs that also boot to MS-Windows normally use
* the local time and change to match daylight savings time. That affects
* attributes including date, time, since_epoch, and wakealarm.
*/
static ssize_t
name_show(struct device *dev, struct device_attribute *attr, char *buf)
{
return sprintf(buf, "%s\n", to_rtc_device(dev)->name);
}
static DEVICE_ATTR_RO(name);
static ssize_t
date_show(struct device *dev, struct device_attribute *attr, char *buf)
{
ssize_t retval;
struct rtc_time tm;
retval = rtc_read_time(to_rtc_device(dev), &tm);
if (retval == 0) {
retval = sprintf(buf, "%04d-%02d-%02d\n",
tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
}
return retval;
}
static DEVICE_ATTR_RO(date);
static ssize_t
time_show(struct device *dev, struct device_attribute *attr, char *buf)
{
ssize_t retval;
struct rtc_time tm;
retval = rtc_read_time(to_rtc_device(dev), &tm);
if (retval == 0) {
retval = sprintf(buf, "%02d:%02d:%02d\n",
tm.tm_hour, tm.tm_min, tm.tm_sec);
}
return retval;
}
static DEVICE_ATTR_RO(time);
static ssize_t
since_epoch_show(struct device *dev, struct device_attribute *attr, char *buf)
{
ssize_t retval;
struct rtc_time tm;
retval = rtc_read_time(to_rtc_device(dev), &tm);
if (retval == 0) {
unsigned long time;
rtc_tm_to_time(&tm, &time);
retval = sprintf(buf, "%lu\n", time);
}
return retval;
}
static DEVICE_ATTR_RO(since_epoch);
static ssize_t
max_user_freq_show(struct device *dev, struct device_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq);
}
static ssize_t
max_user_freq_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t n)
{
struct rtc_device *rtc = to_rtc_device(dev);
unsigned long val = simple_strtoul(buf, NULL, 0);
if (val >= 4096 || val == 0)
return -EINVAL;
rtc->max_user_freq = (int)val;
return n;
}
static DEVICE_ATTR_RW(max_user_freq);
/**
* rtc_sysfs_show_hctosys - indicate if the given RTC set the system time
*
* Returns 1 if the system clock was set by this RTC at the last
* boot or resume event.
*/
static ssize_t
hctosys_show(struct device *dev, struct device_attribute *attr, char *buf)
{
#ifdef CONFIG_RTC_HCTOSYS_DEVICE
if (rtc_hctosys_ret == 0 &&
strcmp(dev_name(&to_rtc_device(dev)->dev),
CONFIG_RTC_HCTOSYS_DEVICE) == 0)
return sprintf(buf, "1\n");
else
#endif
return sprintf(buf, "0\n");
}
static DEVICE_ATTR_RO(hctosys);
static struct attribute *rtc_attrs[] = {
&dev_attr_name.attr,
&dev_attr_date.attr,
&dev_attr_time.attr,
&dev_attr_since_epoch.attr,
&dev_attr_max_user_freq.attr,
&dev_attr_hctosys.attr,
NULL,
};
ATTRIBUTE_GROUPS(rtc);
static ssize_t
rtc_sysfs_show_wakealarm(struct device *dev, struct device_attribute *attr,
char *buf)
{
ssize_t retval;
unsigned long alarm;
struct rtc_wkalrm alm;
/* Don't show disabled alarms. For uniformity, RTC alarms are
* conceptually one-shot, even though some common RTCs (on PCs)
* don't actually work that way.
*
* NOTE: RTC implementations where the alarm doesn't match an
* exact YYYY-MM-DD HH:MM[:SS] date *must* disable their RTC
* alarms after they trigger, to ensure one-shot semantics.
*/
retval = rtc_read_alarm(to_rtc_device(dev), &alm);
if (retval == 0 && alm.enabled) {
rtc_tm_to_time(&alm.time, &alarm);
retval = sprintf(buf, "%lu\n", alarm);
}
return retval;
}
static ssize_t
rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr,
const char *buf, size_t n)
{
ssize_t retval;
unsigned long now, alarm;
unsigned long push = 0;
struct rtc_wkalrm alm;
struct rtc_device *rtc = to_rtc_device(dev);
char *buf_ptr;
int adjust = 0;
/* Only request alarms that trigger in the future. Disable them
* by writing another time, e.g. 0 meaning Jan 1 1970 UTC.
*/
retval = rtc_read_time(rtc, &alm.time);
if (retval < 0)
return retval;
rtc_tm_to_time(&alm.time, &now);
buf_ptr = (char *)buf;
if (*buf_ptr == '+') {
buf_ptr++;
if (*buf_ptr == '=') {
buf_ptr++;
push = 1;
} else
adjust = 1;
}
alarm = simple_strtoul(buf_ptr, NULL, 0);
if (adjust) {
alarm += now;
}
if (alarm > now || push) {
/* Avoid accidentally clobbering active alarms; we can't
* entirely prevent that here, without even the minimal
* locking from the /dev/rtcN api.
*/
retval = rtc_read_alarm(rtc, &alm);
if (retval < 0)
return retval;
if (alm.enabled) {
if (push) {
rtc_tm_to_time(&alm.time, &push);
alarm += push;
} else
return -EBUSY;
} else if (push)
return -EINVAL;
alm.enabled = 1;
} else {
alm.enabled = 0;
/* Provide a valid future alarm time. Linux isn't EFI,
* this time won't be ignored when disabling the alarm.
*/
alarm = now + 300;
}
rtc_time_to_tm(alarm, &alm.time);
retval = rtc_set_alarm(rtc, &alm);
return (retval < 0) ? retval : n;
}
static DEVICE_ATTR(wakealarm, S_IRUGO | S_IWUSR,
rtc_sysfs_show_wakealarm, rtc_sysfs_set_wakealarm);
/* The reason to trigger an alarm with no process watching it (via sysfs)
* is its side effect: waking from a system state like suspend-to-RAM or
* suspend-to-disk. So: no attribute unless that side effect is possible.
* (Userspace may disable that mechanism later.)
*/
static inline int rtc_does_wakealarm(struct rtc_device *rtc)
{
if (!device_can_wakeup(rtc->dev.parent))
return 0;
return rtc->ops->set_alarm != NULL;
}
void rtc_sysfs_add_device(struct rtc_device *rtc)
{
int err;
/* not all RTCs support both alarms and wakeup */
if (!rtc_does_wakealarm(rtc))
return;
err = device_create_file(&rtc->dev, &dev_attr_wakealarm);
if (err)
dev_err(rtc->dev.parent,
"failed to create alarm attribute, %d\n", err);
}
void rtc_sysfs_del_device(struct rtc_device *rtc)
{
/* REVISIT did we add it successfully? */
if (rtc_does_wakealarm(rtc))
device_remove_file(&rtc->dev, &dev_attr_wakealarm);
}
void __init rtc_sysfs_init(struct class *rtc_class)
{
rtc_class->dev_groups = rtc_groups;
}